Rock-drill bit.



G. R. FORBES.

BOOK DRILL BIT. APPLIOATI N FILED 111111: 9, 1913.

1,094,063 I Patented Apr. 21, 1914 .Abbfifib a inventor: '1

.0. Forbes ays.

CARROLL R. roaBEs, or 1mm, MISSOURI.

, ROCK-DRILL BIT.

Specification of'Letters Patent. Patented Apr. 21, 1914.

Application filed June a, 1913. serial No. 772,558.

ToaZZ whom it may concern Be it known that I, CARROLL R. FORBES, acitizen of the United States of America, residing at Rolla, in thecounty of Phelps and State of Missouri, have invented cer tain new anduseful Improvements in Rock- Drill Bits, of which the following is afull, clear, and exact description, reference belng had to theaccompanying drawings, forming a part of this specification- Myinvention relates to rock drill bits of the radial wing or cross type.Bits of this kind as usually constructed have their wings tapered orbeveled longitudinally at their ends to provide sharp edges which extendalong the wings from the axis of the bit to the outer edges of thewings. In the use of such bits, the preponderance ofwear is at the outeredges of'the wings, due to the severest drilling action being performednearest the wall of the hole formed by the drill bit. The period ofseiwiceability of bits of this kind when made with tapering edgesextending to the outer edges of the wings, as heretofore, has beendependent upon the durability of the material present at the outer edgesof the wings of the bits, The wings of the bits being taperedlongitudinally of the bit to the outer edge of the wings so that thewings are thin at such edges, the material at'the outer edges of thewings'hasworn away rapidly, and the outer edge portions of the wingssoon become 1 rounded and ineffective for any period.

My invention has for its object to so construct a rock drill bit of theradial wing type as to render the outer edges of the wings of the bitmore durableby so forming the ends 'of the wings as to prevent rapidwearingfaway of the outer edges of the wings, thereby enhancing theperiod of considerable serviceability of the drill bit and the speed atwhich a hole may be produced in-the use of the bit.

Figure I is an elevation of my drill bit with a portion of its shankbroken off. Fig. II is a view looking at the cutting end of the bit.Fig. III isa cross sectiontaken on line IIIIII Fig'.' I. I

In the drawings: 1 designates the-radial. wings of my bit which extendoutwardly from a common axis.- These wings have inclined faces 2 attheir ends extending longitudinally of the bit and converging towardeach other from the'sides of the wings, the said inclined facespreferably coming together adjacent to the axis of the bit to producesharp edges 2, similar to those in the well known radial wing rock drillbits.

The ends of the wings of my bit are formed with flattened portions4twhich e:;-

tend from the outer edges of the wings, the

flattened portions being widest at the outer .edges of the wings andnarrowing toward the axis of the bit as clearly seen-in Fig. II. Byproviding my bit with the flattened portions 4 I furnish the wings ofthe bit with a greater amount of wear resisting material at their ends.and ad acent to then-outer edges. than is present 1n the old and commonform of radial wing bits, and, as are-- sult of so doing, I haveproduced a bit which will. owing to the greater amount of materialpresent to be worn away at the outer edges of its wings. perfornritsfunctions more lastingly and operate at a greater speed for a givenlength of time than drill bits of the same type as heretofore made.

I claim 1.- A radial wing drill bit having its wings taperedlongitudinally, the said wings being flattened at their ends adjacenttheir outer edges.

2. A radial wing drill bit having its wings tapered longitudinally, thesaid wings having flattened faces extending from their. outer edgestoward the axis of the bit; said flattened faces being widest atv theedges of the wings. and narrowing toward the axis of the bit.

0. R. FORBES.

LARK, E. B. LINN.

